Antibiotics are widely used in human and veterinary medicine for the prevention and treatment of bacterial infectious diseases. An important but often disregarded aspect of antibiotic use is the fate of antibiotic residues entering the environment. Pharmaceutical industry wastewater, improperly-disposed of unused antibiotics, and non-metabolized antibiotics excreted by humans can all enter the sewer system in low concentrations. Because sewage treatment plants are rarely equipped to filter these drugs from wastewater, antibiotics are released into the water system. Veterinary antibiotics used in livestock operations are another major source of antibiotics in the environment. Agricultural waste such as manure and water runoff can carry these antibiotics into the soil and groundwater.
The effects of antibiotics in the environment are still poorly understood. One major concern is the development of antibiotic resistant strains of bacteria that could critically disturb the natural bacteria ecosystems and lead to a serious threat to human health. There are also concerns that, exposure to environmental antibiotic residues might lead to carcinogenic or allergic reactions in humans and create hazards to aquatic and soil organisms